Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2002
Autoantibodies associated with volatile anesthetic hepatitis found in the sera of a large cohort of pediatric anesthesiologists.
Anesthetic-induced hepatitis is thought to have an immune-mediated basis, in part because many patients who develop hepatitis have serum autoantibodies that react with specific hepatic proteins. The present study shows that pediatric anesthesiologists also have these serum autoantibodies. Moreover, levels of these autoantibodies are higher than those of general anesthesiologists. We collected sera from 105 pediatric and 53 general anesthesiologists (including 3 nurse anesthetists), 20 halothane hepatitis patients, and 20 control individuals who were never exposed to inhaled anesthetics. Serum cytochrome P450 2E1 (P450 2E1) and 58-kd hepatic endoplasmic reticulum protein (ERp58) autoantibodies were measured by enzyme-linked immunosorbent assays. Positive values were 2 SD above median control values. Two multiple regression models were constructed. Pediatric anesthesiologists, like halothane hepatitis patients, had higher serum autoantibody levels of ERp58 and P450 2E1 than general anesthesiologists and controls, which was possibly because of their increased occupational exposures to anesthetics. Female anesthesiologists had higher levels of ERp58 autoantibodies than male anesthesiologists, whereas female pediatric anesthesiologists had higher levels of P450 2E1 autoantibodies than all other anesthesiologists. One female pediatric anesthesiologist had symptoms of hepatic injury. Because most anesthesiologists do not develop volatile anesthetic-induced hepatic injury, the findings suggest that pathogenic ERp58 and P450 2E1 autoantibodies may not directly cause volatile anesthetic hepatitis. Female anesthesiologists have high levels of these autoantibodies; however, the majority of these individuals do not develop hepatitis, suggesting that autoantibodies may not have a pathological role in volatile anesthetic-induced hepatitis. ⋯ Environmental exposure of anesthesiology personnel to certain inhaled anesthetics can induce the formation of autoantibodies that have been associated with anesthetic hepatitis. Female anesthesiologists have high levels of these autoantibodies; however, the majority of these individuals do not develop hepatitis, suggesting that autoantibodies may not have a pathological role in volatile anesthetic-induced hepatitis.
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Anesthesia and analgesia · Feb 2002
Comparative StudyElectrocardiographic electrodes provide the same results as expensive special sensors in the routine monitoring of anesthetic depth.
The Bispectral Index (BIS) is a mathematically derived electroencephalographic (EEG) derivative that has been introduced to monitor depth of anesthesia (1,2). The A-2000 BIS monitoring system (Aspect Medical Systems, Inc., Newton, MA) is currently the only commercially available system to monitor depth of anesthesia. In several studies, its propensity to optimize the use of hypnotics to maintain and achieve a certain depth of anesthesia has been described (3,4). Some studies have even proposed that the routine use of the monitoring system can decrease awareness (1,5), an increasing factor in malpractice claims. The cost-benefit calculations for BIS monitoring suffer from the fact that like its predecessor, the 1000-A BIS monitor, the A-2000 BIS monitoring system demands the use of expensive, special electrodes (6). Although the application of the single-use BIS sensor is very comfortable and easy to use, its high price of approximately $10-20 US prevents many anesthesiologists from using it. Furthermore, whereas the former model of the monitor (1000-A BIS monitor; Aspect Medical Systems, Inc.) used standardized connectors, which allowed the use of other electrodes such as electrocardiogram (ECG), the new monitoring system makes this very difficult because of special connectors that match the equivalent connector at the proximal BIS sensor site. The purpose of this prospective study was to compare BIS values derived from the original BIS sensor with BIS values derived from commercially available ECG electrodes. This comparison was made possible by designing and manufacturing a connector allowing the use of ECG electrodes. ⋯ The Bispectral Index (BIS) monitor adequately monitors depth of anesthesia. The routine use of this monitor has been hampered by the benefit-cost equation because only special expensive electrodes can be used. We examined the agreement of BIS values obtained by original sensor electrodes and commercial electrocardiogram (ECG) electrodes. These ECG electrodes can replace more expensive BIS sensors.
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Anesthesia and analgesia · Feb 2002
Venous air emboli occur during release of positive end-expiratory pressure and repositioning after sitting position surgery.
We studied the effect of positive end-expiratory pressure (PEEP) release and positioning on the occurrence of venous air embolism (VAE). Eighteen consecutive patients (8 women, 10 men; ASA grade I-III) undergoing neurosurgery in the sitting position were studied. After induction of anesthesia ventilation was controlled with a PEEP of 5 cm H(2)O in an oxygen-air gas mixture. A transesophageal echocardiographic (TEE) probe was inserted. Preoperatively, a patent foramen ovale was excluded in all patients. TEE monitoring was performed during surgery, during PEEP release at the end of surgery with the patient still in the sitting position, and during change of the patient position into the supine position. The severity of VAE was differentiated as follows: grade 1 = only microbubbles; grade 2 = microbubbles and decrease of end-tidal carbon dioxide partial pressure (PETCO(2)) by more than 1.5 mm Hg; grade 3 = microbubbles combined with a decrease of PETCO(2) by more than 1.5 mm Hg, and a decrease of mean arterial blood pressure by at least 20 mm Hg. During surgery, VAE with a grade of 1, 2 or 3 occurred in 7, 4, and 2 patients, respectively. After PEEP release, VAE of grades 1, 2, and 3 were observed in 7, 2, and 1 patients, respectively. During repositioning from sitting to supine position, VAE of grades 1, 2, and 3 was observed in 6, 1, and 1 patients, respectively. The patient with VAE grade 3 needed inotropic support until 2 h after surgery to maintain sufficient blood pressure. No patient showed any sign of paradoxical arterial embolism or cardiac dysfunction. We conclude that VAE occurs not only during surgery in the sitting position, but also with release of PEEP and during repositioning to the supine position. ⋯ This study shows that venous air embolism (VAE) occurs not only during surgery in the sitting position but also during positive end-expiratory pressure release and repositioning of the patient into the supine position. Continuous monitoring for VAE should be performed until the patient is returned to the supine position.
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Anesthesia and analgesia · Feb 2002
Preserved CO(2) reactivity and increase in middle cerebral arterial blood flow velocity during laparoscopic surgery in children.
In adult patients, the creation of pneumoperitoneum (PP) by means of carbon dioxide (CO(2)) insufflation leads to an increase in cerebral blood flow velocity (CBFV), which is thought to be caused by hypercapnia. We evaluated whether PP leads to an increase of CBFV in children, and whether this increase is directly related to PP. The effects of PP on middle cerebral artery blood flow velocity were investigated in 12 children (mean age 3 yr, range 15-63 mo) undergoing laparoscopic herniorrhaphy under general anesthesia with sevoflurane and nitrous oxide/oxygen. CBFV was measured by using transcranial Doppler ultrasonography. During CO(2) insufflation, the end-tidal CO(2) concentration was kept constant by adjustment of ventilation by increasing minute volume. The CBFV increased significantly at an intraabdominal pressure of 12 mm Hg compared with baseline from 68 +/- 11 cm/s to 81 +/- 12 cm/s (P < 0.05). CO(2) reactivity remained in the normal range (4.0% +/- 1.9%/mm Hg) during PP. We conclude that the induction of PP leads to an increase in middle cerebral artery blood flow velocity in young children independent from hypercapnia, whereas CO(2) reactivity remains normal. ⋯ Laparoscopic surgery is performed frequently in pediatric patients. Cerebral blood flow velocities increase during insufflation of the intraperitoneal cavity for minimally invasive surgery in children. The vasoreactivity as part of the cerebral autoregulation remains unaffected.
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Anesthesia and analgesia · Feb 2002
Comparative StudyThe neurotoxicity of local anesthetics on growing neurons: a comparative study of lidocaine, bupivacaine, mepivacaine, and ropivacaine.
Local anesthetics can be neurotoxic. To test the hypothesis that exposure to local anesthetics produces morphological changes in growing neurons and to compare this neurotoxic potential between different local anesthetics, we performed in vitro cell biological experiments with isolated dorsal root ganglion neurons from chick embryos. The effects of lidocaine, bupivacaine, mepivacaine, and ropivacaine were examined microscopically and quantitatively assessed using the growth cone collapse assay. We observed that all local anesthetics produced growth cone collapse and neurite degeneration. However, they showed significant differences in the dose response. The IC(50) values were approximately, 10(-2.8) M for lidocaine, 10(-2.6) M for bupivacaine, 10(-1.6) M for mepivacaine, and 10(-2.5) M for ropivacaine at 15 min exposure. Some reversibility was observed after replacement of the media. At 20 h after washout, bupivacaine and ropivacaine showed insignificant percentage growth cone collapse in comparison to their control values whereas those for lidocaine and mepivacaine were significantly higher than the control values. Larger concentrations of the nerve growth factor (NGF) did not improve this reversibility. In conclusion, local anesthetics produced morphological changes in growing neurons with significantly different IC(50). The reversibility of these changes differed among the four drugs and was not influenced by the NGF concentration. ⋯ Local anesthetics induce growth cone collapse and neurite degeneration in the growing neurons. Mepivacaine was safer than lidocaine, bupivacaine, and ropivacaine for the primary cultured chick neurons.